Thromboxane synthetase enzyme inhibiting N-[(1H-imidazol-1-yl) and (1H-1,2,4-triazol-1-yl)alkyl]pyridinecarboxamides

ABSTRACT

This invention concerns novel N-[(1H-imidazol-1-yl) and (1H-1,2,4-triazol-1-yl)alkyl]pyridinecarboxamides which are useful as inhibitors of thromboxane synthetase and/or as hypotensive agents in the treatment of hypertension and myocardial ischemia.

SUMMARY OF THE INVENTION

This invention relates to new organic compounds and, more particularly, is concerned with novel N-[(1H-imidazol-1-yl) and (1H-1,2,4-triazol-1-yl)alkyl]pyridinecarboxamides which may be represented by the following structural formula: ##STR1## wherein R₁ is selected from the group consisting of hydrogen and halogen; R₂ and R₃ may be the same or different and are selected from the group consisting of hydrogen, lower alkyl(C₁ -C₃) and phenyl; A is selected from the group consisting of nitrogen and >CH; and n is an integer from 2 to 8, together with the pharmaceutically acceptable salts thereof.

The novel compounds of the present invention are obtainable, in general, as white or pale yellow crystalline solids and in some cases may be oils. The solids have characteristic melting points and absorption spectra. The compounds are appreciably soluble in many organic solvents such as lower alkanols, chloroform, dichloromethane, tetrahydrofuran, acetone, N,N-dimethylformamide and the like, but are relatively insoluble in water.

The organic bases of the present invention form nontoxic acid-addition salts with a variety of pharmacologically acceptable organic and inorganic salt-forming reagents. Thus, acid-addition salts, formed by admixture of the organic free base with one or more equivalents of an acid, suitably in a neutral solvent, are formed with such acids as sulfuric, phosphoric, hydrochloric, hydrobromic, sulfamic, citric, lactic, malic, succinic, maleic, fumaric, tartaric, acetic, benzoic, gluconic, ascorbic and the like. For purposes of this invention the free bases are equivalent to their nontoxic acid-addition salts. The acid-addition salts of the organic bases of this invention are, in general, relatively soluble in water, methanol and ethanol but relatively insoluble in nonpolar organic solvents such as diethyl ether, benzene and toluene.

The N-[(1H-imidazol-1-yl) and (1H-1,2,4-triazol-1-yl)alkyl]pyridinecarboxamides of this invention inhibit thromboxane synthetase enzyme without interfering with other enzymes in the arachadonic acid cascade. The novel compounds of this invention also are active antihypertensive agents.

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the present invention may be prepared according to the following reaction schemes wherein R₁, R₂, R₃, A and n are as described hereinabove. ##STR2##

In accordance with Method I, an appropriately substituted pyridine carboxylic acid (1) is reacted with 1,1'-carbonyldiimidazole in an inert solvent such as tetrahydrofuran at ambient temperature for 1-3 hours to provide the intermediates (2). Treatment of the intermediates (2) with an appropriately substituted 1H-imidazole-1-alkanamine or 1H-1,2,4-triazole-1-alkanamine (3), either as the free base or a salt thereof, provides the final products (4). The final condensation of (2) and (3) is best carried out by adding (3) to the reaction mixture at ambient temperature and allowing to stand or, preferably, heating the mixture at reflux for about 2-6 hours. The addition of aqueous base (potassium hydroxide or sodium hydroxide) and a solvent such as chloroform or carbon tetrachloride results in isolation of the product from the organic phase.

This invention also pertains to N-[(1H-imidazol-1-yl) and (1H-1,2,4-triazol-1-yl)alkyl]-1H-isoindole-1,3(2H)-diones which may be represented by the following structural formula: ##STR3## wherein n is an integer from two to eight, inclusive and R₂ and R₃ are as hereinbefore defined. These phthalimide derivatives are intermediates for the preparation of the hereinbefore described 1H-imidazole(and 1H-1,2,4-triazole)-1-alkanamines (3). The novel 1,3(2H)-dione intermediates (7) may be readily prepared and used to prepare the 1H-imidazole(and 1H-1,2,4-triazole)-1-alkanamines (3) as set forth in the following reaction scheme (Method II) wherein n, R₂, R₃ and A are as hereinbefore defined and X is chloro or bromo. ##STR4##

In accordance with Method IIA, an appropriately substituted 1H-imidazole or 1H-1,2,4-triazole (6) is first converted to a salt form with sodium amide, sodium hydride, and the like and then condensed with an appropriate N-haloalkylphthalimide (5) for about 4-8 hours, to obtain the corresponding 2-[(1H-imidazol-1-yl) or (1H-1,2,4-triazol-1-yl)alkyl]-1H-isoindole-1,3(2H)-dione intermediate (7), which is then reacted with hydrazine hydrate in ethanol at reflux for about 2-8 hours. Hydrochloric acid is then added and refluxing is continued for about 1-6 hours, giving the 1H-imidazole(or 1H-1,2,4-triazole)-1-alkanamine, dihydrochloride (3). The dihydrochloride (3) may be converted to the free base by treatment of an aqueous solution of the dihydrochloride with sodium or potassium hydroxide and extraction with a solvent such as chloroform or dichloromethane, then isolation from the organic phase.

In accordance with Method II B, acrylonitrile (8) and a 1H-imidazole or 1H-1,2,4-triazole (9) are reacted with heat for about 2-4 hours, concentrated to an oil and then hydrogenated with Raney nickel catalyst in methanol and ammonium hydroxide for a period of about 8-10 hours, giving the 1H-imidazole(or 1H-1,2,4-triazole)-1-propanamine derivatives (10).

The compounds of this invention inhibit thromboxane synthetase enzyme without interfering with other enzymes in the arachadonic acid cascade. Thus, these compounds are useful in the treatment of diseases characterized by an imbalance of thromboxane A₂ /prostacyclin such as ischemic heart disease, transient ischemic attack, thrombosis and migraine. Recent reviews have established the role of the thromboxane/prostacyclin balance in the vascular system [Cardiovascular Diseases: New Trends in Surgical and Medical Apsects, H. Barnett, P. Paoletti, E. Flamm and G. Brambilla, eds., Elsevier/North-Holland Biomedical Press, pp 137-150 (1981)].

Prostacyclin (PGI₂) is a potent vasodilator and platelet aggregation inhibitor, whereas thromboxane (TXA₂) is a powerful vasoconstrictor and causative of platelet aggregation. TXA₂ is synthesized by thromboxane synthetase enzyme located in, for example, blood platelets. When TXA₂ production is increased relative to PGI₂, platelet aggregation, thrombosis and vasospasm may occur [Lancet, 1, 1216 (1977); Lancet, 1, 479 (1977); Science, 193, 1135 (1976); Amer. J. Cardiology, 41, 787 (1978)]. TXA₂ synthetase inhibitors have been shown to have superior anti-thrombotic action to that of aspirin [J. Clin. Invest., 65, 400 (1980); Br. J. Pharmac., 76, 3 (1982)].

The role of prostaglandins including TXA₂ and PGI₂ in ischemic heart patients has been reviewed [Cardiovascular Pharmacology of the Prostaglandins, A. G. Herman, P. M. Vanhoute, H. Denolin and A. Goosens, eds., Raven Press, New York, pp 361-374 (1982)]. Injection of TXA₂ into coronary arteries of guinea pigs and rabbits causes myocardial ischemia and subendocardial necrosis [Drugs of the Future, 7, 331 (1982); Proc. Jap. Acad., 53(B), 38 (1977); Eur. J. Pharmacol., 53 49(1978)]. Recent research has demonstrated the beneficial effects of PGI₂ and selective inhibition of thromboxane synthetase on ischemic myocardium in canines [J. Cardiovascular Pharmacology, 4, 129 (1982)]. Thus compounds which selectively inhibit thromboxane synthetase (and hence TXA₂) without adversely affecting PGI₂ are useful in the treatment of vascular diseases such as ischemia and migraine. In addition, inhibition of TXA₂ formation may effectively treat platelet aggregation and prevent thrombosis.

The inhibition of thromboxane (TXA₂) formation was studied by determining the concentration of thromboxane B₂ (TXB₂), the stable hydrolysis product of TXA₂.

Under urethan anesthesia, 10 μl of arterial blood was collected in one ml of 3.2% sodium citrate in a polystyrene tube from Okamoto-Aoki spontaneously hypertensive rats (SHR) (Taconic Farms, Germantown, NY) between 19 and 24 weeks in age. The blood was diluted with 3 ml cold saline and centrifuged at room temperature for 15 minutes at 460 xg. The platelet rich plasma (PRP) was separated. The platelets were isolated by centrifuging the PRP for 10 minutes at 1060 xg and were washed in 4 ml cold oxygenated Krebs phosphate buffer, pH 7.4. The chilled platelets recovered from centrifuging at 800 xg for 10 minutes were resuspended in oxygenated Krebs phosphate buffer and diluted to contain 4.5-6.0×10⁴ platelets/μl. Assay samples, prepared on ice, contained 200 μl platelet suspension, 50 μl saline, and 50 μl vehicle or drug under study (OKY-1581, UK-37248-01, 1-benzylimidazole, or indomethacin). The samples were incubated for 10 minutes at 37° C. in a metabolic shaker. The reaction was terminated by immersing the tubes in an ice bath and adding 50 μl of 0.5M citric acid. The samples were centrifuged for 10 minutes in a refrigerated centrifuge and the supernatants thus obtained were decanted and stored at -20° C. The TXB₂ content for each sample was determined by a direct radioimmunoassay (RIA) utilizing a TXB₂ specific RIA kit purchased from New England Nuclear, Boston, Mass. and expressed as pg TXB₂ formed minute⁻¹ sample⁻¹, from which the percent inhibition of TXB₂ formation was calculated. The results of this test on representative compounds of this invention appear in Table I below.

                  TABLE I                                                          ______________________________________                                                                Dose                                                    Compound               (M)    % Inhibition                                     ______________________________________                                         N--[3-(1H--Imidazol-1-yl)propyl]-2-                                                                   10.sup.-4                                                                             59                                               pyridinecarboxamide                                                            2-Chloro-N--[3-(1H--imidazol-1-yl)pro-                                                                10.sup.-4                                                                             58                                               pyl]-3-pyridinecarboxamide                                                     6-Chloro-N--[3-(1H--imidazol-1-yl)pro-                                                                10.sup.-4                                                                             88                                               pyl]-3-pyridinecarboxamide                                                     6-Chloro-N--[3-(1H--1,2,4-triazol-1-yl)-                                                              10.sup.-4                                                                             67                                               propyl]-3-pyridinecarboxamide                                                  N--[4-(1H--Imidazol-1-yl)butyl]-2-                                                                    10.sup.-4                                                                             82                                               pyridinecarboxamide, fumarate                                                  6-Chloro-N--[3-(4-methyl-1H--imidazol-                                                                10.sup.-4                                                                             86                                               1-yl)propyl]-3-pyridinecarboxamide                                             6-Chloro-N--[3-(2-methyl-1H--imidazol-1-                                                              10.sup.-4                                                                             44                                               yl)propyl]-3-pyridinecarboxamide                                               2-Chloro-N--[3-(2-methyl-1H--imidazol-                                                                10.sup.-4                                                                             38                                               1-yl)propyl]-3-pyridinecarboxamide                                             6-Chloro-N--[3-(2-phenyl-1H--imidazol-1-                                                              10.sup.-4                                                                             56                                               yl)propyl]-3-pyridinecarboxamide                                               N--[3-(4-Methyl-1H--imidazol-1-yl)pro-                                                                10.sup.-4                                                                             50                                               pyl]-3-pyridinecarboxamide                                                     6-Chloro-N--[4-(1H--imidazol-1-yl)-                                                                   10.sup.-4                                                                             94                                               butyl]-3-pyridinecarboxamide                                                   2-Chloro-N--[3-(4-methyl-1H--imidazol-                                                                10.sup.-4                                                                             50                                               1-yl)propyl]-3-pyridinecarboxamide                                             N--[3-(2-Phenyl-1H--imidazol-1-yl)pro-                                                                10.sup.-4                                                                             30                                               pyl]-2-pyridinecarboxamide                                                     6-Chloro-N--[3-(1H--imidazol-1-yl)-                                                                   10.sup.-4                                                                             98                                               2-methylpropyl]-3-pyridinecarboxamide                                          6-Chloro-N--[3-(1H--imidazol-1-yl)-                                                                   10.sup.-4                                                                             98                                               butyl]-3-pyridinecarboxamide                                                   N--[3-(4-Methyl-1H--imidazol-1-yl)-                                                                   10.sup.-4                                                                             84                                               propyl]-2-pyridinecarboxamide                                                  N--[3-(1H--Imidazol-1-yl)propyl]-3-                                                                   10.sup.-4                                                                             83                                               pyridinecarboxamide                                                            2-Chloro-N--[4-(1H--imidazol-1-yl)-                                                                   10.sup.-4                                                                             90                                               butyl]-3-pyridinecarboxamide                                                   ______________________________________                                    

The novel compounds of the present invention also are active antihypertensive agents and were tested for hypotensive activity by the method of P. S. Chan and D. Poorvin, Clinical and Experimental Hypertension, 1 (6), 817-830 (1979). Male, 16 week old, spontaneously hypertensive rats of the Okamoto strain, from Taconic Farms, Germantown, N.Y., having an average mean arterial blood pressure of 160±1.5 mm of mercury are used in the test. One to three rats are used per test compound. A rat is dosed by gavage with a test compound, suspended in 2% pre-boiled starch at a concentration of 50 mg/ml, at a dose of 100 mg/kg of body weight or less with 0.9% sodium chloride loading at a dose of 25 ml/kg of body weight. A second identical dose of the test compound without sodium chloride loading is given 24 hours later. At 28 hours after the initial dose the mean arterial blood pressure is measured by the method of Chan and Poorvin vide supra. The procedure is repeated in a second and third rat when necessary.

The results of this test on representative compounds of the present invention appear in Table II below

                  TABLE II                                                         ______________________________________                                                                 MABP in mm Hg                                          Compound                (no. of rats)                                          ______________________________________                                         N--[3-(1H--Imidazol-1-yl)propyl]-2-pyridine-                                                           127 (4)                                                carboxamide                                                                    6-Chloro-N--[3-(1H--imidazol-1-yl)propyl]-                                                             132 (3)                                                3-pyridinecarboxamide                                                          6-Chloro-N--[3-(1H--1,2,4-triazol-1-yl)-                                                               140 (2)                                                propyl]-3-pyridinecarboxamide                                                  N--[4-(1H--Imidazol-1-yl)butyl]-2-pyridine-                                                            116 (2)                                                carboxamide, fumarate                                                          6-Chloro-N--[3-(4-methyl-1H--imidazol-1-yl)-                                                           139 (2)                                                propyl]-3-pyridinecarboxamide                                                  N--[3-(4-Methyl-1H--imidazol-1-yl)propyl]-                                                             123 (1)                                                3-pyridinecarboxamide                                                          N--[3-(4-Methyl-1H--imidazol-1-yl)propyl]-                                                             140 (3)                                                2-pyridinecarboxamide                                                          N--[3-(1H--Imidazol-1-yl)propyl]-3-pyridine-                                                           138 (2)                                                carboxamide                                                                    6-Chloro-N--[3-(1H--imidazol-1-yl)-2-methyl-                                                           129 (3)                                                propyl]-3-pyridinecarboxamide                                                  6-Chloro-N--[3-(1H--imidazol-1-yl)-butyl]-                                                             111 (2)                                                3-pyridinecarboxamide                                                          ______________________________________                                    

The novel compounds of the present invention have been found to be highly useful for inhibiting thromboxane synthetase and/or lowering elevated blood pressure in mammals when administered in amounts ranging from about 0.1 mg to about 20.0 mg/kg of body weight per day. A preferred dosage regimen for optimum results would be from about 0.5 mg to about 10.0 mg/kg of body weight per day. Such dosage units are employed that a total of from about 35 to about 700 mg of active compound for a subject of about 70 kg of body weight are administered in a 24 hour period. This dosage regimen may be adjusted to provide the optimum therapeutic response. For example, several divided doses may be administered daily or the dose may be proportionally reduced as indicated by the exigencies of the therapeutic situation. The compounds of this invention are preferably administered orally but may be administered in any convenient manner such as by the intravenous, intramuscular, or subcutaneous routes.

Compositions according to the present invention having the desired clarity, stability and adaptability for parenteral use are obtained by dissolving from 0.10% to 10.0% by weight of active compound in a vehicle consisting of a polyhydric aliphatic alcohol or mixtures thereof. Especially satisfactory are glycerin, propylene glycol, and polyethylene glycols. The polyethylene glycols consist of a mixture of non-volatile, normally liquid, polyethylene glycols which are soluble in both water and organic liquids and which have molecular weights of from about 200 to 1500. Although the amount of active compound dissolved in the above vehicle may vary from 0.10% to 10.0% by weight, it is preferred that the amount of active compound employed be from about 3.0% to about 9.0% by weight. Although various mixtures of the aforementioned non-volatile polyethylene glycols may be employed, it is preferred to use a mixture having an average molecular weight of from about 200 to about 400.

In addition to the active compound, the parenteral solutions may also contain various preservatives which may be used to prevent bacterial and fungal contamination. The preservatives which may be used for these purposes are, for example, myristyl-gamma-picolinium chloride, benzalkonium chloride, phenethyl alcohol, p-chlorophenyl-alpha-glycerol ether, methyl and propyl parabens and thimerosal. As a practical matter, it is also convenient to employ antioxidants. Suitable antioxidants include, for example, sodium bisulfite, sodium metabisulfite and sodium formaldehyde sulfoxylate. Generally, from about 0.05% to about 0.2% concentrations of antioxidant are employed.

For intramuscular injection, the preferred concentration of active compound is 0.25 to 0.50 mg/ml of the finished compositions. The novel compounds of the present invention are equally adapted to intravenous administration when diluted with water or diluents employed in intravenous therapy such as isotonic glucose in appropriate quantities. For intravenous use, initial concentrations down to about 0.05 to 0.25 mg/ml of active ingredient are satisfactory.

The active compounds of the present invention may be orally administered, for example, with an inert diluent or with an assimilable edible carrier, or they may be enclosed in hard or soft shell gelatin capsules, or they may be compressed into tablets, or they may be incorporated directly with the food of the diet. For oral therapeutic administration, the active compounds may be incorporated with excipients and used in the form of tablets, troches, capsules, elixirs, suspensions, syrups, wafers and the like. Such compositions and preparations should contain at least 0.1% of active compound. The percentage of the compositions and preparations may, of course, be varied and may conveniently be between about 2% to about 60% of the weight of the unit. The amount of active compound in such therapeutically useful compositions is such that a suitable dosage will be obtained.

The tablets, troches, pills, capsules and the like may also contain the following: A binder such as gum tragacanth, acacia, corn starch or gelatin; excipients such as dicalcium phosphate; a disintegrating agent such as corn starch, potato starch, alginic acid and the like; a lubricant such as magnesium stearate; and a sweetening agent such as sucrose, lactose or saccharin may be added or a flavoring agent such as peppermint, oil of wintergreen or cherry flavoring may be added. When the dosage unit form is a capsule, it may contain, in addition to materials of the above type, a liquid carrier such as a fatty oil. Various other materials may be present as coatings or to otherwise modify the physical form of the dosage unit. For instance, tablets, pills or capsules may be coated with shellac, sugar or both. A syrup or elixir may contain the active compound, sucrose as a sweetening agent, methyl and propylparabens as preservatives, a dye and flavoring such as cherry or orange flavor. Of course, any material used in preparing any dosage unit form should be pharmaceutically pure and substantially nontoxic in the amounts employed.

The following specific examples illustrate the preparation of the compounds of the present invention and should not be construed to limit this invention in any way.

EXAMPLE 1 1H-imidazole-1-propanamine

A mixture of 41 g of imidazole and 75 ml of acrylonitrile was heated on a steam bath for 3 hours, then concentrated under reduced pressure to remove excess acrylonitrile. A 300 ml portion of methanol was added to the residue together with 100 ml of concentrated ammonium hydroxide and 8 g of Raney nickel catalyst. This mixture was hydrogenated in a Parr apparatus until hydrogen uptake ceased and then filtered giving a light green liquid. A 300 ml portion of tetrahydrofuran was added to this liquid and the mixture filtered through diatomaceous earth. The filtrate was concentrated twice from toluene, giving 75.2 g of the desired intermediate as a clear oil. The dihydrochloride salt may be obtained by treating the base with ethanolic hydrochloric acid, concentration and recrystallization from ethanol.

EXAMPLE 2 4-Methyl-1H-imidazole-1-propanamine

A mixture of 49.2 g of 4-methyl-1H-imidazole and 75 ml of acrylonitrile was heated on a steam bath for 6 hours and then concentrated to remove excess acrylonitrile. The residue was diluted with 400 ml of methanol and divided into two parts. To each was added 90 ml of ammonium hydroxide and Raney nickel catalyst. Each portion was then hydrogenated in a Parr apparatus. Each part was filtered, the filtrates combined and concentrated. The residue was concentrated from toluene. This residue was dissolved in tetrahydrofuran, stirred for one hour, filtered, concentrated, then concentrated from toluene, giving 82.2 g of the desired intermediate as an oil. Alternatively, and preferably, the portions can be purified by distillation through a Kugelrohr apparatus to produce the desired intermediate as an oil.

By substituting the appropriate imidazole starting material in the above procedure, the following intermediates were prepared: 2-methyl-1H-imidazole-1-propanamine; 2-ethyl-1H-imidazole-1-propanamine; 2,4-dimethyl-1H-imidazole-1-propanamine; 2-phenyl-1H-imidazole-1-propanamine; and 4-phenyl-1H-imidazole-1-propanamine.

EXAMPLE 3 3-(1H-Imidazol-1-yl)-2-methylpropanamine

A mixture of 15.0 g of imidazole and 25 ml of methacrylonitrile was heated at reflux temperature for 18 hours and then concentrated to remove the volatile material. The residue was mixed with 150 ml of ethanol, 75 ml of ammonium hydroxide and 6 g of Raney nickel catalyst and reduced in a Parr hydrogenator under hydrogen pressure until reduction was complete. The catalyst was removed by filtration and the mother liquor was concentrated to remove the solvents. The residual oil was used in reactions without further purification.

When the above procedure is used to react imidazole with crotononitrile, 3-(1H-imidazol-1-yl)butanamine is obtained.

EXAMPLE 4 2-[4-(1H-Imidazol-1-yl)butyl]-1H-isoindole-1,3(2H)-dione

A mixture of 0.2 mole of N-(4-bromobutyl)-1H-isoindole-1,3(2H)-dione, 0.22 mole of sodium imidazole and 300 ml of dimethylformamide was stirred at 100° C. for 8 hours and then concentrated to remove the dimethylformamide. The residue was boiled with 500 ml of toluene and the insoluble material was removed by filtration. The toluene layer was concentrated to remove the solvent and the residue was further purified by HPLC using ethyl acetate and a PrepPAK®-500 Silica column (Waters Associates, Millipore). The desired compound melted at 75°-77° C. Addition of ethanolic hydrogen chloride resulted in the hydrocloride salt, mp 200°-203° C.

When the above procedure was used to react sodium imidazole with the appropriate 2-(ω-bromoalkyl)-1H-isoindole-1,3(2H)-dione, the compounds of Table III were obtained.

                  TABLE III                                                        ______________________________________                                         Ex.  Compound                   MP °C.                                  ______________________________________                                         5    2-[5-(1H--imidazol-1-yl)pentyl]-1H--isoindole-                                                            194-197                                             1,3(2H)--dione hydrochloride                                              6    2-[6-(1H--imidazol-1-yl)hexyl]-1H--isoindole-                                                             83-87                                               1,3(2H)--dione                                                            7    2-[7-(1H--imidazol-1-yl)heptyl]-1H--isoindole-                                                            oil                                                 1,3(2H)--dione                                                            8    2-[8-(1H--imidazol-1-yl)octyl]-1H--isoindole-                                                             43-45                                               1,3(2H)--dione                                                            ______________________________________                                    

EXAMPLE 9 1H-Imidazole-1-butanamine

A mixture of 0.2 mole of 2-[4-(1H-imidazol-1-yl)butyl]-1H-isoindole-1,3(2H)-dione, 0.22 mole of hydrazine hydrate and 400 ml of ethanol was heated on a steam bath for 3 hours and then treated with 400 ml of 3N hydrochloric acid and then heated at reflux for an additional 2 hours. The insoluble material was filtered off and the mother liquor was concentrated to a low volume and again filtered. The remainder of the volatile material was distilled off and the residue was treated with saturated potassium carbonate solution. The 1H-imidazole-1-butanamine was extracted into methylene chloride and further purified by distillation on a Kugelrohr apparatus. In like manner from the appropriate 2-[ω-(1H-imidazol-1-yl)alkyl]-1H-isoindole-1,3(2H)-diones were prepared 1H-imidazole-1-pentanamine; 1H-imidazole-1-hexanamine; 1H-imidazole-1-heptanamine; and 1H-imidazole-1-octanamine.

EXAMPLE 10 1H-1,2,4-Triazole-1-butanamine, dihydrochloride

A mixture of 9.0 g of 1H-1,2,4-triazole, 6.24 g of approximately 50% sodium hydride in oil and 130 ml of dimethylformamide was stirred for 1.5 hours. Then, 33 g of N-(4-bromobutyl)phthalimide was added and this mixture was heated on a steam bath for 6 hours, then concentrated to a solid residue. Water and methylene chloride were added, the organic layer was separated, washed with water, dried and concentrated to a residue. This residue was recrystallized from ethanol, giving 27.3 g of 2-[4-(1H-1,2,4-triazol-1-yl)butyl]-1H-isoindol-1,3(2H)-dione.

A mixture of 27 g of the above dione, 4.85 ml of hydrazine hydrate and 250 ml of ethanol was refluxed for 3 hours and then cooled. A 450 ml portion of 3N hydrochloric acid was added and the mixture was refluxed for about 3 hours, then concentrated to 1/2 volume and filtered. The filtrate was concentrated to a solid which was reconcentrated twice from ethanol, giving 18.2 g of the desired intermediate as white crystals, mp 183°-186° C.

EXAMPLE 11 1H-1,2,4-Triazole-1-ethanamine, dihydrochloride

A mixture of 25.4 g of N-(2-bromoethyl)phthalimide, 10.0 g of sodium triazole and 300 ml of dimethylformamide was heated on a steam bath for 3 hours and then concentrated. The residue was heated twice on a steam bath with a total of 400 ml of toluene, filtered and then cooled, giving 10.1 g of 2-[4-(1H-1,2,4-triazol-1-yl)ethyl]-1H-isoindol-1,3(2H)-dione.

A mixture of 7.5 g of the above dione, 1.70 ml of hydrazine hydrate and 120 ml of ethanol was refluxed for 3 hours, then cooled and 160 ml of approximately 3N hydrochloric acid was added. This mixture was refluxed for about 2 hours, then concentrated. Water was added and the mixture filtered. The filtrate was concentrated and the residue recrystallized twice from ethanol, giving 6.1 g of the desired intermediate as a white solid, mp 200°-210° C.

EXAMPLE 12 1H-1,2,4-Triazole-1-propanamine

A mixture of 20.7 g of 1H-1,2,4-triazole and 37.5 ml of acrylonitrile was heated on a steam bath for 3 hours and then concentrated to an oil. This oil was added to 200 ml of methanol and 100 ml of concentrated ammonium hydroxide containing Raney nickel catalyst in a Parr apparatus and hydrogenated for 8 hours with an uptake of about 46 psi of hydrogen. The catalyst was removed by filtration and ethanol was added to the filtrate. The mixture was filtered, the filtrate was concentrated, then reconcentrated from toluene, giving 36.6 g of the desired intermediate as an oil.

EXAMPLE 13 1H-1,2,4-Triazole-1-pentanamine

A mixture of 5.92 g of N-(5-bromopentyl)phthalimide, 2.07 g of sodium triazole and 25 ml of dimethylformamide was heated in an oil bath at 100° C. for 9 hours and then concentrated to remove the solvent. Methylene chloride was added and the insoluble material removed by filtration. The methylene chloride layer was washed with water, dried and concentrated. The residue was treated with ethanolic hydrochloric acid and ether and the crystalline material recovered by filtration. On recrystallization from ethanol, 2-[5-(1H-1,2,4-triazole-1-yl)pentyl]-1H-isoindol-1,3(2H)-dione, hydrochloride, mp 185°-188° C. was obtained.

A mixture of 7.4 g of the above dione, 2.2 g of sodium carbonate and 10 ml of water was stirred and methylene chloride was added. The layers were separated and the organic layer dried and concentrated to remove the solvent. The residual oil, 1.0 ml of hydrazine hydrate and 80 ml of ethanol were refluxed for about 3 hours, cooled and 100 ml of approximately 3N hydrochloric acid was added. This mixture was refluxed for 2 hours, concentrated, water was added and the mixture was filtered. The filtrate was concentrated to remove volatile material and the crude dihydrochloride salt was treated with saturated potassium carbonate solution and extracted with methylene chloride. The organic layer was dried over magnesium sulfate and concentrated to obtain the desired compound as an oil.

EXAMPLE 14 N-[3-(1H-Imidazol-1-yl)propyl]-2-pyridinecarboxamide

A mixture of 1.85 g of picolinic acid and 2.43 g of 1,1'-carbonyldiimidazole in 50.0 ml of tetrahydrofuran was stirred at room temperature for 3 hours. A 3.0 g amount of 1H-imidazole-1-propanamine, dihydrochloride was added and the mixture was stirred for 16 hours. The mixture was heated at reflux for 6 hours, treated with 5 ml of water and heated 30 minutes longer. The mixture was concentrated, dichloromethane was added plus 50 ml of 1N sodium hydroxide. The mixture was shaken and the organic layer was separated, washed twice with water, dried and concentrated to give 3.0 g of an oil. The oil was slurried with diethyl ether and the compound of the Example was obtained as white crystals, mp 75°-77° C.

Following the general procedure of Example 14 and reacting the appropriate pyridinecarboxylic acid derivative with 1,1'-carbonyldiimidazole and 1H-imidazol-1-propanamine in tetrahydrofuran, the compounds of Examples 15-17 found in Table IV were prepared.

                  TABLE IV                                                         ______________________________________                                              Pyridine-                                                                 Ex.  carboxylic Acid                                                                             Compound          MP °C.                              ______________________________________                                         15   2-Chloronicotinic                                                                           2-Chloro-N--[3-(1H--imida-                                                                       103-105                                         acid         zol-1-yl)propyl]-3-                                                            pyridinecarboxamide                                          16   6-chloronicotinic                                                                           6-Chloro-N--[3-(1H--imida-                                                                       145-147                                         acid         zol-1-yl)propyl]-3-                                                            pyridinecarboxamide                                          17   Nicotinic acid                                                                              N--[3-(1H--Imidazol-1-yl)-                                                                       112-114                                                      propyl]-3-pyridinecar-                                                         boxamide                                                     ______________________________________                                    

EXAMPLE 18 6-Chloro-N-[3-(1H-1,2,4-triazol-1-yl)propyl]-3-pyridinecarboxamide

A mixture of 2.37 g of 6-chloronicotinic acid and 2.43 g of 1,1'-carbonyldiimidazole in 50 ml of tetrahydrofuran was stirred at room temperature for 2 hours. A 1.9 ml amount of 1H-1,2,4-triazole-1-propanamine was added and the mixture was stirred for 16 hours. The procedure as described in Example 14 was continued and gave 2.0 g of an oil. The oil was treated with diethyl ether and gave 1.3 g of the desired compound as yellow crystals, mp 87°-89° C.

EXAMPLE 19 6-Chloro-N-[5-(1H-1,2,4-triazol-1-yl)pentyl]-3-pyridinecarboxamide

The above compound is obtained when 1H-1,2,4-triazole-1-pentanamine is reacted with 6-chloronicotinic acid by the procedure of Example 18.

EXAMPLE 20 6-Chloro-N-[3-(4-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

A mixture of 4.73 g of 6-chloronicotinic acid and 4.86 g of 1,1'-carbonyldiimidazole in 100 ml of tetrahydrofuran was stirred at room temperature for 3 hours. Then 4.6 g of 4-methyl-1H-imidazole-1-propanamine was added and stirring was continued for 16 hours. The mixture was heated at reflux for 3 hours, 15 ml of water was added and refluxing was continued for 2 hours longer. The mixture was concentrated and 200 ml of dichloromethane and 30 ml of 1N sodium hydroxide were added. The mixture was shaken and the dichloromethane layer was separated, washed twice with water, dried over magnesium sulfate, filtered and evaporated to an oil. On standing, crystals separated and, with the addition of ether, pale yellow crystals were collected by filtration. The material was recrystallized from ethyl acetate and gave 5.81 g of the compound of the Example as pale yellow crystals, mp 106°-110° C.

Following the general procedure of Example 20 and reacting the appropriate pyridinecarboxylic acid derivative with 1,1'-carbonyldiimidazole and 4-methyl-1H-imidazole-1-propanamine in tetrahydrofuran, the compounds of Examples 21-23 found in Table V were prepared.

                  TABLE V                                                          ______________________________________                                              Pyridinecarboxylic                                                        Ex.  Acid          Compound         MP °C.                              ______________________________________                                         21   Nicotinic acid                                                                               N--[3-(4-Methyl-1H--                                                                            113-118                                                       imidazol-1-yl)propyl]-                                                         3-pyridinecarboxamide                                       22   2-Chloronicotinic                                                                            2-Chloro-N--[3-(4-methyl-                                                                       133-143                                         acid          1H--imidazol-1-yl)pro-                                                         pyl]-3-pyridinecar-                                                            boxamide                                                    23   Picolinic acid                                                                               N--[3-(4-Methyl-1H--                                                                            oil                                                           imidazol-1-yl)propyl]-2-                                                       pyridinecarboxamide                                         ______________________________________                                    

EXAMPLE 24 6-Chloro-N-[3-(2-ethyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

When 2-ethyl-1H-imidazole-1-propanamine is substituted for 4-methyl-1H-imidazole-1-propanamine in the procedure of Example 20, the above compound is obtained.

EXAMPLE 25 6-Chloro-N-[3-(1H-imidazol-1-yl)butyl]-3-pyridinecarboxamide

When 6-chloronicotinic acid was reacted with 3-(1H-imidazol-1-yl)butanamine by the procedure of Example 20 the desired compound was obtained, mp 137°-139° C.

EXAMPLE 26 6-Chloro-N-[3-(1H-imidazol-1-yl)-2-methylpropyl]-3-pyridinecarboxamide

When 6-chloronicotinic acid was reacted with 3-(1H-imidazol-1-yl)-2-methylpropanamine by the procedure of Example 20, the compound of the Example was obtained, mp 102°-104° C.

EXAMPLE 27 N-[4-(1H-Imidazol-1-yl)butyl]-2-pyridinecarboxamide, fumarate

A mixture of 1.23 g of picolinic acid and 1.62 g of 1,1'-carbonyldiimidazole in 30 ml of tetrahydrofuran was stirred at room temperature for 3 hours. Then 2.12 g of 1H-imidazole-1-butanamine, dihydrochloride was added and the mixture was stirred for 16 hours. The mixture was heated at reflux for 5 hours, treated with 5 ml of water and heated for 30 minutes longer. The mixture was concentrated and then dichloromethane was added plus 30 ml of 1N sodium hydroxide. The mixture was shaken and the organic layer was separated, washed twice with water, dried over magnesium sulfate, filtered and concentrated to an oil. The oil was treated with ether, then with ethyl acetate. Evaporation of the solvents gave 1.7 g of an oil. A portion of the oil was dissolved in ethanol and treated with fumaric acid at a ratio of 1:1 and gave 1.7 g of the desired compound as white crystals, mp 113°-115° C.

Following the general procedure of Example 27 and reacting the appropriate pyridinecarboxylic acid derivative with 1,1'-carbonyldiimidazole and 1H-imidazole-1-butanamine, either as the free base or a salt thereof in tetrahydrofuran, the compounds of Examples 28-29 found in Table VI were obtained.

                  TABLE VI                                                         ______________________________________                                              Pyridinecarboxylic                                                        Ex.  Acid          Compound        MP °C.                               ______________________________________                                         28   6-Chloronicotinic                                                                            6-Chloro-N--[4-(1H--                                                                           95-97                                            acid          imidazol-1-yl)butyl]-3-                                                        pyridinecarboxamide                                         29   2-Chloronicotinic                                                                            2-Chloro-N--[4-(1H--                                                                           oil                                              acid          imidazol-1-yl)butyl]-3-                                                        pyridinecarboxamide                                         ______________________________________                                    

EXAMPLE 30 6-Chloro-N-[3-(2-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

A mixture of 2.36 g of 6-chloronicotinic acid and 2.43 g of 1,1'-carbonyldiimidazole in 60 ml of tetrahydrofuran was stirred at room temperature for 2 hours. Then, 2.08 g of 2-methyl-1H-imidazolepropanamine was added and the mixture was stirred at room temperature for 48 hours. The white precipitate which formed on the walls of the flask was collected by filtration, washed with ether and gave 3.2 g of the compound of the Example as cream colored crystals, mp 175°-177° C.

EXAMPLE 31 6-Chloro-N-[3-(2,4-dimethyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

When 2,4-dimethyl-1H-imidazole-1-propanamine is treated with a mixture of 6-chloronicotinic acid and 1,1'-carbonyldiimidazole by the procedure of Example 30 the compound of the Example is obtained.

EXAMPLE 32 2-Chloro-N-[3-(2-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

A mixture of 2.36 g of 2-chloronicotinic acid and 2.43 g of 1,1'-carbonyldiimidazole in 60 ml of tetrahydrofuran was stirred at room temperature for 2 hours. Then, 2.08 g of 2-methyl-1H-imidazole-1-propanamine was added and the mixture was stirred at room temperature for 48 hours. The clear solution was heated at reflux for 4 hours then 10 ml of water was added and heating was continued for one hour longer. The mixture was concentrated then dichloromethane was added plus 10 ml of 1N sodium hydroxide. The mixture was shaken and the organic layer was separated, washed twice with water, dried over magnesium sulfate and filtered. The solution was concentrated and gave 3.6 g of an oil. The oil was treated with diethyl ether and gave 2.8 of yellow crystals. The material was recrystallized from ethyl acetate and gave 2.0 g of the desired compound as cream colored crystals, mp 126°-128° C.

EXAMPLE 33 6-Chloro-N-[3-(2-phenyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

A mixture of 2.36 g of 6-chloronicotinic acid and 2.43 g of 1,1'-carbonyldiimidazole in 60 ml of tetrahydrofuran was stirred at room temperature for 2 hours. Then, 3.0 g of 2-phenyl-1H-imidazole-1-propanamine was added and the mixture was stirred at room temperature for 48 hours. The mixture was heated at reflux for 2 hours, 10 ml of water was added and heating was continued for one hour longer. The mixture was concentrated then dichloromethane was added plus 10 ml of 1N sodium hydroxide. The mixture was shaken and the organic layer was separated, washed twice with water, dried over magnesium sulfate and filtered. The filtrate was concentrated and gave 6.4 g of a viscous oil. The oil was treated by preparative high pressure liquid chromatography using a PrepPAK®-500 Silica column (Waters Associates, Millipore) and ethyl acetate as eluent. Fractions were collected and fractions 7, 8 and 9 were concentrated and gave 4.7 g of an oil. The oil was treated with diethyl ether to crystallize 3.9 g of the compound of the Example as white crystals, mp 84°-86° C.

EXAMPLE 34 6-Chloro-N-[3-(4-phenyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide

The above compound is obtained when 4-phenyl-1H-imidazole-1-propanamine is substituted for 2-phenyl-1H-imidazole-1-propanamine in the procedure of example 33.

EXAMPLE 35 N-[3-(2-Phenyl-1H-imidazol-1-yl)propyl]-2-pyridinecarboxamide

A mixture of 1.85 g of picolinic acid and 2.43 g of 1,1'-carbonyldiimidazole in 60 ml of tetrahydrofuran was stirred at room temperature for 2 hours. Then 3.0 g of 2-phenyl-1H-imidazole-1-propanamine was added and the procedure as described in Example 33 was continued to obtain 5.7 g of a viscous oil. The oil was treated by preparative high pressure liquid chromatography using a PrepPAK®-500 Silica column (Waters Associates, Millipore) and ethyl acetate as eluent. Fractions were collected and fractions 5 and 6 were concentrated, treated with ether, and dried and gave 3.8 g of the compound of the Example as an oil.

EXAMPLE 36 6-Chloro-N-[8-(1H-imidazol-1-yl)octyl]-3-pyridinecarboxamide

A mixture of 1.58 g of 6-chloronicotinic acid and 1.62 g of 1,1'-carbonyldiimidazole in 30 ml of tetrahydrofuran was stirred at room temperature for 3 hours. Then 1.95 g of 1H-imidazole-1-octanamine was added and the mixture was stirred at room temperature for 16 hours. The mixture was heated at reflux for 5 hours, 10 ml of water was added and heating was continued for one hour longer. The mixture was concentrated to remove tetrahydrofuran. Then 5 ml of 1N sodium hydroxide and dichloromethane was added. The mixture was shaken and the organic layer was separated, washed twice with water, dried over magnesium sulfate and filtered. The filtrate was concentrated and gave an oil. The oil was treated with diethyl ether to crystallize the desired compound as white crystals, mp 79°-81° C.

EXAMPLE 37 6-Chloro-N-[5-(1H-imidazol-1-yl)pentyl]-3-pyridinecarboxamide

A mixture of 1.58 g of 6-chloronicotinic acid and 1.62 g of 1,1'-carbonyldiimidazole in 30 ml of tetrahydrofuran was stirred at room temperature for 3 hours. Then 1.52 g of 1H-imidazole-1-pentanamine was added. The procedure of Example 36 was followed to conclusion and gave 2.3 g of the compound of the Example as white crystals, mp 110°-112° C.

EXAMPLE 38 6-Chloro-N-[2-(1H-1,2,4-triazol-1-yl)ethyl]-3-pyridinecarboxamide

A mixture of 1.58 g of 6-chloronicotinic acid and 1.62 g of 1,1'-carbonyldiimidazole in 30 ml of tetrahydrofuran was stirred at room temperature for 3 hours. Then 1.11 g of 1H-1,2,4-triazole-1-ethanamine was added and the mixture was stirred at room temperature for 16 hours. The mixture was heated at reflux for 5 hours, 10 ml of water was added and heating was continued for one hour longer. The mixture was concentrated to remove tetrahydrofuran. Then 5 ml of 1N sodium hydroxide and dichloromethane were added. The mixture was shaken and the precipitate was collected by filtration and gave 1.7 g of the compound as white crystals, mp 186°-188° C. 

We claim:
 1. A compound of the formula: ##STR5## wherein R₁ is selected from the group consisting of hydrogen and halogen; R₂ and R₃ may be the same or different and are selected from the group consisting of hydrogen, lower alkyl(C₁ -C₃) and phenyl; A is selected from the group consisting of nitrogen and >CH; n is an integer from 2 to 8 inclusive; and the pharmaceutically acceptable salts thereof.
 2. The compound according to claim 1; N-[3-(1H-imidazol-1-yl)propyl]-2-pyridinecarboxamide.
 3. The compound according to claim 1; 2-chloro-N-[3-(1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 4. The compound according to claim 1; 6-chloro-N-[3-(1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 5. The compound according to claim 1; N-[3-(1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 6. The compound according to claim 1; 6-chloro-N-[3-(1H-1,2,4-triazol-1-yl)propyl]-3-pyridinecarboxamide.
 7. The compound according to claim 1; 6-chloro-N-[3-(4-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 8. The compound according to claim 1; N-[3-(4-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 9. The compound according to claim 1; 2-chloro-N-[3-(4-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 10. The compound according to claim 1; N-[3-(4-methyl-1H-imidazol-1-yl)propyl]-2-pyridinecarboxamide.
 11. The compound according to claim 1; N-[4-(1H-imidazol-1-yl)butyl]-2-pyridinecarboxamide, fumarate.
 12. The compound according to claim 1; 6-chloro-N-[4-(1H-imidazol-1-yl)butyl]-3-pyridinecarboxamide.
 13. The compound according to claim 1; 2-chloro-N-[4-(1H-imidazol-1-yl)butyl]-3-pyridinecarboxamide.
 14. The compound according to claim 1; 6-chloro-N-[3-(2-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 15. The compound according to claim 1; 2-chloro-N-[3-(2-methyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 16. The compound according to claim 1; 6-chloro-N-[3-(2-phenyl-1H-imidazol-1-yl)propyl]-3-pyridinecarboxamide.
 17. The compound according to claim 1; N-[3-(2-phenyl-1H-imidazol-1-yl)propyl]-2-pyridinecarboxamide.
 18. The compound according to claim 1; 6-chloro-N-[8-(1H-imidazol-1-yl)octyl]-3-pyridinecarboxamide.
 19. The compound according to claim 1; 6-chloro-N-[5-(1H-imidazol-1-yl)pentyl]-3-pyridinecarboxamide.
 20. The compound according to claim 1; 6-chloro-N-[2-(1H-1,2,4-triazol-1-yl)ethyl]-3-pyridinecarboxamide.
 21. The compound according to claim 1; 6-chloro-N-[5-(1H-1,2,4-triazol-1-yl)pentyl]-3-pyridinecarboxamide.
 22. The compound according to claim 1; 6-chloro-N-[3-(1H-imidazol-1-yl)butyl]-3-pyridinecarboxamide.
 23. The compound according to claim 1; 6-chloro-N-[3-(1H-imidazol-1-yl)-2-methylpropyl]-3-pyridinecarboxamide.
 24. A method of inhibiting thromboxane synthetase enzyme in a mammal which comprises administering internally to said mammal a thromboxane synthetase enzyme inhibiting amount of a compound of the formula as recited in claim
 1. 25. A method of lowering elevated blood pressure in a mammal which comprises administering internally to said mammal a blood pressure lowering amount of a compound of the formula as recited in claim
 1. 26. A thromboxane synthetase enzyme inhibiting composition of matter in dosage unit form which comprises a compound of the formula as recited in claim 1 in association with a pharmaceutically acceptable carrier.
 27. A thromboxane synthetase enzyme inhibiting composition of matter, as recited in claim 26, wherein the dosage unit comprises from about 10 mg to about 700 mg of the compound in association with the pharmaceutically acceptable carrier.
 28. A blood pressure lowering composition of matter in dosage unit form useful for lowering elevated blood pressure in mammals which comprises a compound of the formula as recited in claim 1 in association with a pharmaceutically acceptable carrier.
 29. A blood pressure lowering composition of matter, as recited in claim 28, wherein the dosage unit comprises from about 10 mg to about 700 mg of the compound in association with the pharmaceutically acceptable carrier. 